Jessica Fridrich

Rubik's cube 11/25/11 10:51 AM My speed cubing page This is a copy of Ernö Rubik's signature as it appears in my notebook. He signed it at the World Championship in Budapest in 1982 This system for advanced cubers and is not appropriate for a beginner. It is intended for those of you who can already solve the cube in a few minutes and want to get really fast. If you are a complete beginner, please, visit Jasmine's Beginner Solution. My system for solving Rubik's cube Unique features The first two layers (additional useful hints and examples of how I solve the first two layers) The last layer 20 years of speed cubing (a short historical narrative) Watch me solving the cube Hints for speed cubing Customizing algorithms Multiple algorithms Finger shortcuts Move algorithms to your subconsciousness No delays between algorithms Faster twisting does not have to mean shorter times Preparing the cube for record times Hard work What are the limits of speed cubing? Collections of various algorithms (by Mirek Goljan, mgoljan (AT) binghamton. edu) Swapping two edges and two corners http://ws2.binghamton.edu/fridrich/cube.html Page 1 of 2 Rubik's cube 11/25/11 10:51 AM Swaping two and two edges Twisting and moving corners and edges in one layer (by Mirek Goljan, mgoljan (AT) binghamton. edu) Pretty patterns by Mirek Goljan, mgoljan (AT) binghamton. edu Richard Carr is THE expert on solving large cubes with a list of his record times. Richard can solve the cube blindfolded and willingly shares with us his method. I met Richard in April 2003 and he showed me his incredible skills in person. Guus Razoux Schultz on speed cubing The World Championship, Budapest 1982 Hana Bizek's cube art Dutch Cube Day, October 6, 2002 San Francisco Cubing, January 19, 2003 The 2nd World Championship in Rubik's Cube in Toronto, August 23-24, 2003 Press&Sun Bulletin, Binghamton Sep 11, 2003 Cube links http://ws2.binghamton.edu/fridrich/cube.html Page 2 of 2 System for solving Rubik's cube 11/25/11 10:52 AM My system for solving Rubik's cube Winter 1996/97: The system described here enabled me to win the First Czechoslovak Championship in Rubik's Cube, which took place in April 1982. When I was at my best, I routinely solved the cube in an average time of 17 seconds. At that time, I was actively using more than 100 algorithms, but the basic required minimum is 53 algorithms. Before I go on and describe the details of my system, I would like to express my thanks to Mike Pugh who retyped the algorithms from my old notebook to HTML and added nice graphics. His enthusiasm helped me to find the cube no less interesting than some 15+ years ago when I met it for the first time. Special thanks belong to Mirek Goljan, my 1982 finale rival, who kindly provided his enormous collection of algorithms as it appears here today. There are a number of diferent systems suitable for speed cubing, but all can be roughly divided into two main categories: corners-edges and by-layers. My system belongs to the second category even though the first two layers are really formed at the same time rather than in sequence. The basic set of algorithms consists of 53 algorithms for the last layer and a couple of simple moves for the second layer together with a lot of experience. Most of the algorithms were developed by myself during the time period between the summer 1981 and the spring of 1983. However, other speed cubists, most noticeably Mirek Goljan, have also significantly contributed with important moves. Here is my system in a nut shell: Average number Action description Time Result of moves Place the four edges from the first layer 7 2 sec. Place four blocks each consisting of one corner from the first layer and a 4 x 2 4 x 7 corresponding sec. edge from the second layer. Simultaneously orient the corners AND http://ws2.binghamton.edu/fridrich/system.html#unique Page 1 of 3 System for solving Rubik's cube 11/25/11 10:52 AM edges 9 3 sec. so that the last layer has the required color (one algorithm out of 40). Simultaneously permute the 8 cubes in the last layer without rotating corners or flipping 12 4 sec. edges (one algorithm out of 13). TOTAL 56 17 Unique features One of the unique features of this system is that the last layer is always solved using two algorithms of an average length of 9 and 12, which is very efficient. The average lengths are based on frequencies with which various orientations and permutations occur and on the length of algoritms for each position. Another interesting feature is that for the first two layers no lengthy algorithms are needed and you can use your intuition and utilize the specifics of the particular initial state and subsequent states of the cube. The first two layers In an attempt to make this description complete, I supplied several algorithms which can help you solve the first two layers. Although most of the algorithms will be obvious to an experienced speed cubist, some of them are less trivial and are in my opinion very valuable. In addition to that, one should always try to use the specifics of any given state of the cube rather than blindly apply the algorithms. For example, when two or three corners are already correctly placed, it may be advantageous to keep the last corner free and insert all middle cubes using the free corner. Actually, some speed cubists use this approach as their default. Alternatively, when accidentaly (or intentionally) two or more middle cubes happen to be positioned correctly, one can place the corners from the first layer via the free middle edge(s). All these moves and http://ws2.binghamton.edu/fridrich/system.html#unique Page 2 of 3 System for solving Rubik's cube 11/25/11 10:52 AM a lot of practice should enable you to solve the first two layers in about 10-12 sec. Of course, this requires a lot of practicing, but let us say that 15-20 sec. will be realistic for most folks. Because I was receiving a lot of requests for "additional hints" and advice for the middle layer, I decided to include another section with practical advice for solving the middle layer. Here are a few examples of how I think out loud when doing the middle layer. I hope this will help you to master the system faster! The last layer Some systems for solving Rubik's cube "by-layers" divide the solution of the last layer into four stages: orient edges, place edges, orient corners, place corners. It is possible to group together two and two stages to speed up the process. It seems natural to orient and place edges in one move and then orient and place corners in the second one. However, this approach has one big disadvantage - it is very difficult to recognize various positions quickly. A better approach is to orient edges and corners at the same time and place all of them simultaneously. Convince yourself that there are 41 different orientations of the cubies in the last layer, and 14 different permutations of those 8 cubies. Here, we do not count symmetric positions or inverse (backwards) positions as different because they can be solved using one algorithm. Different orientations are easily recognizable by patterns formed by the color of the last layer and a brief look at the sides of the cube. There are two patterns "C", four "I", two "T", etc. Most of the permutations are also easily recognizable. Given an average twisting speed of three moves per second, one can solve the last layer in 3 + 4 seconds (based on the average number of moves). In theory, we could come up with a much larger system of algorithms which would enable us to solve the last layer in one algorithm. However, the number of algorithms one would need to learn is 1211. http://ws2.binghamton.edu/fridrich/system.html#unique Page 3 of 3 20 years of speedcubing 11/25/11 10:52 AM 20 years of speedcubing Dear visitor, I am sure my narrative will occassionally bring a smile of disbelief to your faces today, but I want to truthfully describe the atmosphere of excitement and mystery as we, the old-timers, lived through the "good ol' days" of the early eighties when Rubik's cube was making headlines around the world. The first time I met the cube "face-to-face" was when I was 16 years old in March 1981. I was hooked since the first moment I saw this absolutely unique combination of simplicity and ingenuity. There was no need to explain what needs to be done with it - a self-explanatory, remarkably difficult puzzle with a devilishly mysterious mechanism inside - a fascinating silent challenge. The owner of the cube was a 14-year old boy who could solve the cube in about a minute. He lent it to me for a few minutes just enough to assemble one face. Although in March 1981 the cube was being sold by thousands in other countries and despite the fact that the invention took place in the neighboring country, it was impossible to buy the cube in Czech Republic. A classical example of how inefficient and impotent the Eastern Block economies were. I got my hands on a primitive solving system from a Russian magazine Kvant long before I actually owned the cube.

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